Abstract
<em>Idli</em> is a common flour based fermented food prepared using lactic acid bacteria which bear probiotic properties, consumed in Sri Lanka and some parts of India. The objective of the present study was to characterize the lactic acid bacteria from <em>idli</em> batter, identify the changes of acidity during fermentation and to determine the antibiotic sensitivity of isolates. Lactic acid bacteria were isolated and characterized up to genus level. Subsequently, antibiotic susceptibility of isolates against four antibiotics was studied. Changes of pH, lactic acid bacterial count and titratable acidity with fermentation were determined. The pH value dropped steadily from 6.28 to 3.72 while titratable acidity increased from 0.24 to 0.92% during the fermentation period of 0 to 32 h. With fermentation, the lactic acid bacterial count was increased up to 9.88 log10cfu/g after 12 hours of fermentation and the count reduced with increasing acidity. A bacterial count of 5.91 log10cfu/g was recorded at the end of 32 hours of fermentation. Ten lactic acid bacteria isolates were identified from <em>idli</em> batter, of which six isolates were rod shaped and other four were cocci. All isolates were Gram positive, non-motile, no n-spore formers and catalase negative. According to the above tests, it was confirmed up to the genus level that all strains be longed to Lactic acid bacteria. All isolates were susceptible to more than two antibiotics. The diameter of the zone of inhibition ranged from 1-23 mm. The highest zone of inhibition was observed in isolates I-6 against chloromphenicol (23 mm) while the lowest zone of inhibition was observed in isolates I-2 against erythromycin (1 mm). With fermentation the biochemic al and sensory qualities of <em>idli</em> batter were changed. Lactic Acid Bacteria isolates showed different sensitivity towards antibiotics tested.
Highlights
Fermentation is considered the oldest food preservation method yet fermented foods are popular even today across the world
Well-developed characteristic presumptive lactic acid bacteria (LAB) were isolated from idli batter
This study reports susceptibility profile of ten strains which were isolated from idli batter against different antibiotics such as Ciprofloaxacin, Chloromphenicol, Amoxicillin and Erythromycin using the disc diffusion method
Summary
Fermentation is considered the oldest food preservation method yet fermented foods are popular even today across the world. Lactic acid bacteria (LAB) play a major role and the optimum amount of acid production varies with the product type. Isolation and screening of new probiotic strains of LAB from fermented products is important as these micro florae may possess strong probiotic functionalities such as the ability to produce organic acids, exopolysaccharides, proteolytic products and production of antimicrobial activity against many foods borne pathogens (El-Soda et al, 2003; Ayad et al, 2004; Abd El Gawad et al, 2010 and Ayad and Shokery, 2011). The resistance character can be transmitted through the food chain in human and subsequently it may transfer to pathogenic bacteria. It is important to evaluate the antibiotic resistance of LAB before use them as food or starter cultures (Rodríguez-Alonso et al, 2009)
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